Binimetinib (Mektovi®)

Author: Christina Bach, MBE, LCSW, OSW-C
Content Contributor: Karen Arnold-Korzeniowski, BSN RN
Last Reviewed: October 16, 2023

Pronounce: bin-i-ME-ti-nib

Classification: Kinase Inhibitor

About: Binimetinib (Mektovi®)

Binimetinib is usually given in combination with another medication called encorafenib. It is used to treat melanoma and some types of lung cancer that have a BRAF V600E or V600K mutation, which is found by testing a piece of the tumor. This article will focus on the side effects of taking binimetinib with encorafenib. If you are taking both medications, please see the article for encorafenib for more information.

A kinase is an enzyme that promotes cell growth. There are many types of kinases, which control different phases of cell growth. By blocking a particular enzyme from working, this medication can slow the growth of cancer cells.

Binimetinib works by targeting and blocking receptors found on cancer cells called BRAF V600E or V600K. In some cancers, this receptor is overactive, causing cells to grow and divide too fast. By slowing or stopping these receptors, this medication can slow or stop tumor growth. Your oncology team will test your tumor for this mutation, which must be there in order to receive the medication.

How to Take Binimetinib

Binimetnib is taken twice a day, by mouth, in tablet form. It can be taken with or without food. If you miss your dose and it is within 6 hours of your next dose, skip the missed dose and take your next dose as scheduled. If you vomit after taking this medication, do not take an extra dose. Instead, continue with your next dose as scheduled. Consult with your pharmacist or provider if you are having trouble swallowing the medication.

It is important to make sure you are taking the correct amount of medication every time. Before every dose, check that what you are taking matches what you have been prescribed.

If at some point you stop taking binimetinib you should also stop taking encorafenib. Discuss with your provider if you stop taking any medication.

Storage and Handling

Store your medication in the original, labeled container at room temperature and in a dry location (unless otherwise directed by your healthcare provider or pharmacist). Ask your pharmacist if this medication can be stored in a pillbox. Keep containers out of reach of children and pets.

If a caregiver prepares your dose for you, they should consider wearing gloves or pour the pills directly from their container into the cap, a small cup, or directly into your hand. They should avoid touching the pills. They should always wash their hands before and after giving you the medication. Pregnant or nursing women should not prepare the dose for you. Ask your oncology team where to return any unused medication for disposal. Do not flush down the toilet or throw in the trash.

Where do I get this medication?

Binimetinib is available through select specialty pharmacies. Your oncology team will work with your prescription drug plan to identify an in-network specialty pharmacy for the distribution of this medication and shipment directly to your home.

Insurance Information

This medication may be covered under your prescription drug plan. Patient assistance may be available to qualifying individuals depending upon prescription drug coverage. Co-pay cards, which reduce the patient co-pay responsibility for eligible commercially (non-government sponsored) insured patients, may also be available. Your care team can help you find these resources if they are available.

Possible Side Effects of Binimetinib

The following side effects are possible when binimetinib and encorafenib are given together. There are a number of things you can do to manage these side effects. Talk to your care team about these recommendations. They can help you decide what will work best for you. These are some of the most common or important side effects:

Muscle Problems

This medication can cause a muscle problem called rhabdomyolysis caused by the increase of an enzyme in your blood called creatine phosphokinase. You will have your lab work checked to monitor for this. You should notify your care provider if you experience weakness, muscle aches or pains, or dark, reddish urine.

Kidney Problems

This medication can cause kidney problems, including an increased creatinine level, which your oncology care team may monitor for using blood tests. Notify your healthcare provider if you notice decreased urine output, blood in the urine, swelling in the ankles, or loss of appetite.


Fatigue is very common during cancer treatment and is an overwhelming feeling of exhaustion that is not usually relieved by rest. While on cancer treatment, and for a period after, you may need to adjust your schedule to manage fatigue. Plan times to rest during the day and conserve energy for more important activities. Exercise can help combat fatigue; a simple daily walk with a friend can help. Talk to your healthcare team for helpful tips on dealing with this side effect.

Nausea and/or Vomiting

Talk to your oncology care team so they can prescribe medications to help you manage nausea and vomiting. In addition, dietary changes may help. Avoid things that may worsen the symptoms, such as heavy or greasy/fatty, spicy, or acidic foods (lemons, tomatoes, oranges). Try saltines, or ginger ale to lessen symptoms.

Call your oncology care team if you are unable to keep fluids down for more than 12 hours or if you feel lightheaded or dizzy at any time.


Your oncology care team can recommend medications to relieve diarrhea. Also, try eating low-fiber, bland foods, such as white rice and boiled or baked chicken. Avoid raw fruits, vegetables, whole grain breads, cereals, and seeds. Soluble fiber is found in some foods and absorbs fluid, which can help relieve diarrhea. Foods high in soluble fiber include applesauce, bananas (ripe), canned fruit, orange sections, boiled potatoes, white rice, products made with white flour, oatmeal, cream of rice, cream of wheat, and farina. Drink 8-10 glasses of non-alcoholic, uncaffeinated fluid a day to prevent dehydration.

Low Red Blood Cell Count (Anemia)

Your red blood cells are responsible for carrying oxygen to the tissues in your body. When the red cell count is low, you may feel tired or weak. You should let your oncology care team know if you experience any shortness of breath, difficulty breathing, or pain in your chest. If the count gets too low, you may receive a blood transfusion.

Less common, but important side effects can include:

  • Liver Toxicity: This medication can cause liver toxicity, which your oncology care team may monitor for using blood tests called liver function tests. Notify your healthcare provider if you notice yellowing of the skin or eyes, your urine appears dark or brown, or you have pain in your abdomen, as these can be signs of liver toxicity.
  • Vision Problems: Eye problems can occur and you should contact your care provider right away if you develop any of these symptoms: blurred vision, loss of vision or any other vision changes, seeing colored dots or halos, eye pain, swelling, or redness.
  • Bleeding: This medication can cause abnormal, serious bleeding. You should contact your provider if you cough up blood or blood clots, when you vomit it looks like coffee grounds or you have red or black, tarry stools.
  • Blood Clots: Contact your care provider if you have any of the following symptoms: chest pain, sudden shortness of breath, pain in your legs with or without swelling, new swelling in your arms or legs, or if any of your arms or legs feels cool.
  • Heart Problems: Your provider will monitor how your heart is functioning. If you have any symptoms such as feeling like your heart is racing, shortness of breath, swelling in your ankles or feet, or you feel lightheaded, call your provider right away.
  • Lung Problems: If you develop new or worsening shortness of breath or a cough, you should contact your care provider.
  • Secondary Malignancies: There is a risk of developing a new primary skin cancer due to treatment with this medication, which can happen during treatment or many years after treatment. You will have frequent skin checks and you should report any new changes in your skin to your provider.

Reproductive Concerns

Exposure of an unborn child to this medication could cause birth defects, so you should not become pregnant or father a child while on this medication. Effective birth control is necessary during treatment and for at least 30 days after treatment. Even if your menstrual cycle stops or you believe you are not producing sperm, you could still be fertile and conceive. You should not breastfeed while receiving this medication, or for 3 days after your last dose.


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